Datasheet ADA4938-1/ADA4938-2 (Analog Devices)

Ultralow Distortion Differential ADC Driver Data Sheet ADA4938-1/ ADA4938-2 FEATURES FUNCTIONAL BLOCK DIAGRAMS Extremely low harmonic distortion (HD) ADA4938-1 TOP VIEW −106 dBc HD2 @ 10 MHz S S S S –V –V –V –V −82 dBc HD2 @ 50 MHz 61 5 3 1 41 1 −109 dBc HD3 @ 10 MHz −82 dBc HD3 @ 50 MHz –FB 1 12 PD Low input voltage noise: 2.6 nV/√Hz +IN 2 11 –OUT High speed –IN 3 10 +OUT +FB 4 9 −3 dB bandwidth of 1000 MHz, G = +1 VOCM Slew rate: 4700 V/μs
1
5 6 7 8
00 2-
0.1 dB gain flatness to 150 MHz S S S S
59
+V +V +V +V
06
Fast overdrive recovery of 4 ns
Figure 1. ADA4938-1 Functional Block Diagram
1 mV typical offset voltage ADA4 938-2 Externally adjustable gain TOP VIEW 1 1 T Differential-to-differential or single-ended-to-differential 1 1 1 B S S 1 U NI F V V D O + – – – P – operation 4 3 2 1 0 2 2 2 2 9 2 1 Adjustable output common-mode voltage –IN1 1 18 +OUT1 Wide supply voltage range: +5 V to ±5 V +FB1 2 17 VOCM1 Single or dual amplifier configuration available +VS1 3 16 –VS2 +VS1 4 15 –VS2 APPLICATIONS –FB2 5 14 PD2 ADC drivers +IN2 6 13 –OUT2 Single-ended-to-differential converters 7 8 9 01 11 21 IF and baseband gain blocks 2 2 2 2 2 2
2
N B S S M T
20
I– F V V C U
2-
+ + + O Differential buffers
59
V O +
06
Line drivers
Figure 2. ADA4938-2 Functional Block Diagram
–50 GENERAL DESCRIPTION G = +2, VO, dm = 5V p-p G = +2, VO, dm = 3.2V p-p –60 G = +2, VO, dm = 2V p-p
The ADA4938-1/ADA4938-2 are low noise, ultralow distortion,
G = +2, VO, dm = 1V p-p –70
high speed differential amplifiers. It is an ideal choice for driving high performance ADCs with resolutions up to 16 bits
–80 Bc) d
from dc to 27 MHz, or up to 12 bits from dc to 74 MHz. The
–90 DR (
output common-mode voltage is adjustable over a wide range,
F S –100
allowing the ADA4938-1/ADA4938-2 to match the input of the
–110
ADC. The internal common-mode feedback loop also provides
–120
exceptional output balance as well as suppression of even-order harmonic distortion products.
–130
2
1 10 100
00
FREQUENCY (MHz)
Full differential and single-ended-to-differential gain configurations 06592- Figure 3. SFDR vs. Frequency and Output Voltage are easily realized with the ADA4938-1/ADA4938-2. A simple external feedback network of four resistors determines the makes them well-suited for a wide variety of data acquisition and closed-loop gain of the amplifier. signal processing applications. The ADA4938-1/ADA4938-2 are fabricated using the Analog The ADA4938-1 (single amplifier) is available in a Pb-free, Devices, Inc., proprietary third generation, high voltage XFCB 3 mm × 3 mm, 16-lead LFCSP. The ADA4938-2 (dual process, enabling it to achieve very low levels of distortion with amplifier) is available in a Pb-free, 4 mm × 4 mm, 24-lead an input voltage noise of only 2.6 nV/√Hz. The low dc offset and LFCSP. The pinouts have been optimized to facilitate layout and excellent dynamic performance of the ADA4938-1/ADA4938-2 minimize distortion. The devices are specified to operate over the extended industrial temperature range of −40°C to +85°C.
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Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAMS REVISION HISTORY SPECIFICATIONS DUAL-SUPPLY OPERATION ±DIN to ±OUT Performance VOCM to ±OUT Performance SINGLE-SUPPLY OPERATION ±DIN to ±OUT Performance VOCM to ±OUT Performance ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Maximum Power Dissipation ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TEST CIRCUTS TERMINOLOGY THEORY OF OPERATION ANALYZING AN APPLICATION CIRCUIT SETTING THE CLOSED-LOOP GAIN ESTIMATING THE OUTPUT NOISE VOLTAGE THE IMPACT OF MISMATCHES IN THE FEEDBACK NETWORKS CALCULATING THE INPUT IMPEDANCE OF AN APPLICATION CIRCUIT INPUT COMMON-MODE VOLTAGE RANGE IN SINGLE-SUPPLY APPLICATIONS TERMINATING A SINGLE-ENDED INPUT SETTING THE OUTPUT COMMON-MODE VOLTAGE LAYOUT, GROUNDING, AND BYPASSING HIGH PERFORMANCE ADC DRIVING OUTLINE DIMENSIONS ORDERING GUIDE